HI all.
I think is your first rig, so my opinion is:
-Be aware "Sophisticated" MOBO that can be a pain, try to use Comercial models with 4 or 5 PCI-e (split your cards)
-Dont use expensive CPU you dont need them, use Semprom or a cheapest 64bit new CPU if exist.
-Use at least 1.5gb RAM for each GPU card, if you have more RAM you can increase TC and avoid HW.
-Dont use a Case, use Open rigs home made is good
-Use Only 24cm Powered Riser, put the cards separately you need air flow
-Buy a big Fan to help air flow in the cards
-Use HD or SSD drive if you can (cheap USB flash are slow, and gonna die any moment)
-I recommend to use Linux, Debian or your_favorite distro, only with X server(_no_ Desktop Env.), ssh server, and AMD drivers
--IF YOU-- dont want to deal with ssh sessions, Terminals, Nano or Vi editor, Compiling Miners, Downloding with wget. USE WIN
Plus, tunning a Rig take from 3days -7days (optimal values)
I hope this can help
P.S.: (Linux)In some MOBO you have to disable Integrated LAN, and use common PCI LAN Card.
I'm sorry, but I have to disagree with some of your advice. Not sure where you got the 1.5GB RAM rule, I have not had any issues running 6 cards on 4GB RAM, from R9 270 to 280X. Recent cgminer clones with xintensty/rawintensity work very well with lower TC values and 2 threads. Risers are probably a matter of preference, I would suggest 50-60cm "USB" type, these are cheap enough, much more reliable and offer a lot more flexibility than short "ribbon" style risers. No need to use "favorite distro" or compile miners - use BAMT (or of course Windows if Linux of any kind is too scary). Cheap USB flash drives are fine for BAMT, for a price of one SSD you can keep a drawer full of replacements in the unlikely event of failure.